The present invention relates to surgical instruments and more particularly, to endoscopic instruments suitable for use with a trocar or cannula.
A branch of endoscopic surgery is laparoscopic surgery which involves the use of a cannula that is inserted through an incision in the skin of the subject to provide access to an internal cavity, such as the thoracic cavity. An example of such a cannula is disclosed in Hasson U.S. Pat. No. 5,002,557, the disclosure of which is incorporated herein by reference. Surgery is performed with a laparoscopic instrument, which typically includes a scissors handle and an elongate shaft terminating in a pair of pivoting jaws. The handle includes a scissors or pliers grip which, when squeezed and released, reciprocates a rod extending through the shaft to pivot the jaws. The jaws and shaft are sized to be inserted through the cannula into the body cavity where the surgery is to be performed. Similar devices are employed in thoroscopic and arthroscopic surgery.
As with any surgical instruments, should the tool include sharpened jaws for cutting, it is desirable to maintain the sharpened edges as sharp as possible for each operation. Further, it is also desirable to design the instrument so that it can be easily and thoroughly cleaned after each operation. However, a disadvantage with unitary instruments--that is, instruments in which the handle, shaft and cutting tool are permanently attached to each other--is that cleaning of the instrument and sharpening of the tool after each operation becomes time-consuming and costly.
Accordingly, attempts have been made to provide laparoscopy instruments which minimize the time and expense of cleaning and sharpening. For example, some laparoscopy instruments are made in which substantially the entire instrument is constructed of plastic, except for the shaft rod and jaws, so that the entire instrument is disposable after each operation. Alternately, instruments such as those disclosed in Falk et al. U.S. Pat. No. 4,569,131 are designed in which the handle is separable from the shaft and jaws, so that the unitary shaft, jaws and rod may be disposed after each use, or cleaned and sharped separately from the handle. A disadvantage with these types of designs is that the disposable component--whether it be the entire instrument or only the shaft and cutting tool--provides an undesirably high volume of medical waste which requires special disposal procedures. Further, disposable instruments made largely of plastic are somewhat flimsy and difficult to maneuver.
Accordingly, there is a need for a laparoscopy instrument which eliminates the need for repeated sharpening of the cutting surfaces of the instrument, facilitates cleaning and reduces cross-contamination potential.